Body campanulate, widest at anterior border, from which it tapers directly to the pedicle. The diameter of the peristome is a little larger than the length of the body. The ciliary disk is but little elevated. The cuticle is not striated and the body plasm is quite transparent. Length 52µ. [Illustration: Fig. 59.--_Vorticella patellina_.] Vorticella marina Greeff. Fig. 60. The body is conical but variable, and may he short or elongate, so that relative length and breadth offer no chance of identification. In general the body is campanulate. The distinguishing feature is the transverse annulation of the bell. Small, but common, and grows in small social groups. Length 35µ. [Illustration: Fig. 60.--_Vorticella marina_.] Genus ZOOTHAMNIUM (Bory de St. Vincent 1824) Stein '38, '54. Colorless and highly contractile forms growing in small or large colonies. The form and structure of the individuals is not different from _Vorticella_. The colonies are usually richly branched upon the dichotomous plan and the entire colony is contractile. The main character is that with each division of the individual the stalk also divides, each daughter cell getting one-half of the parent stem. The stems therefore remain in communication, so that a simultaneous contraction results, and the colony as a whole is withdrawn. In some species so-called macrogonidia, or larger sexual individuals, are developed alongside the usual ones. Fresh and salt water. Zoothamnium elegans D'Udekem '64? Fig. 61. The bodies are variable--peristomial border widely dilated, tapering and attenuate posteriorly. The pedicle is slender, smooth, and transparent, and branches sparsely at its distal extremity. There are but few zooids (3 to 4). The ciliary disk projects conspicuously beyond the peristomial border. The pharyngeal cleft is very distinct and extends beyond center of body. Length of body 80µ. [Illustration: Fig. 61.--_Zoothamnium elegans_.] Genus COTHURNIA (Ehr. '31) Clap. & Lach. '58.